The core

why is the core of our earth so hot? what causes it to be so? and why some other stars and planets like neptune/uranus (i forgot) does no have such a hot core? and what purpose does the molten core of our earth serve?

Originally posted by alchemist
why is the core of our earth so hot?
what causes it to be so?

Friction and nuclear decay of the heavier
elements that "sank in" during Earth's formation.

Originally posted by alchemist
and why some other stars and planets like neptune/uranus (i forgot) does no have such a hot core? and what purpose does the molten core of our earth serve?

In stars there's nuclear fusion of elements in
the center. They're extremely hot inside and
outside.

As for other planets, I believe that the same
thing happens there too, but the specifics
depend on the planet's formation and elements
present. I'm not sure about the way it works
in gas giants though.

I'm not sure what you mean by - "what purpose does
the molten core... serve ?". It's just there.

Staff: Mentor

Originally posted by alchemist why is the core of our earth so hot? what causes it to be so? and why some other stars and planets like neptune/uranus (i forgot) does no have such a hot core? and what purpose does the molten core of our earth serve?

Initally, the heat came from the energy of the material as it condensed to form the Earth. Additional heat is added by the radioactive elements as already mentioned. As the Surface of the Earth cooled, and the Crust formed, the molten interior was surrounded by a natural insulator. This insulation, in the form of solid rock, traps the heat inside pretty effectively.

The gas giants don't have a solid surface, and as such, can lose heat faster.

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Originally posted by alchemist
why is the core of our earth so hot? what causes it to be so? and why some other stars and planets like neptune/uranus (i forgot) does no have such a hot core? and what purpose does the molten core of our earth serve?
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Initally, the heat came from the energy of the material as it condensed to form the Earth. Additional heat is added by the radioactive elements as already mentioned. As the Surface of the Earth cooled, and the Crust formed, the molten interior was surrounded by a natural insulator. This insulation, in the form of solid rock, traps the heat inside pretty effectively.

The gas giants don't have a solid surface, and as such, can lose heat faster.

Also, radioactive elements tend to be of higher atomic number, more common with terrestrial planets.

Originally posted by alchemist and what purpose does the molten core of our earth serve?

Purpose? Like the existential purpose of being? No answer there.

But, the flow of the iron in the core creates a magnetic field for the Earth. The Earth's magnetic field reduces the amount of cosmic rays and ionized particles reaching the Earth's surface (good for us). It also creates the aurorae at the north and south poles.